1. Field of the Invention
The present invention relates to a perpendicular magnetic recording head for recording data on a recording medium, such as a disk having a hard surface, under application of a perpendicular magnetic field. More particularly, the present invention relates to a perpendicular magnetic recording head and a method of manufacturing the head, which can suppress the occurrence of fringing in a recording pattern, can form a main magnetic pole layer with high pattern accuracy and form a yoke surface having a large film thickness, and can improve the passing efficiency of magnetic flux.
2. Description of the Related Art
Conventionally, a perpendicular magnetic recording method is utilized in a device for recording magnetic data on a recording medium, such as a disk, with a high density. FIG. 38 is a sectional view showing a general structure of a perpendicular magnetic recording head for use in the known perpendicular magnetic recording device.
As shown in FIG. 38, a perpendicular magnetic recording head H utilizing the perpendicular magnetic recording method is provided on a side end surface of a slider 1 moving or sliding in a floating relation over a recording medium. On a side end surface la of the slider 1, for example, the perpendicular magnetic recording head H is disposed between a nonmagnetic film 2 and a nonmagnetic coating film 3.
The perpendicular magnetic recording head H has an auxiliary magnetic pole layer 4 made of ferromagnetic materials, and a main magnetic pole layer 5 also made of ferromagnetic materials and formed above the auxiliary magnetic pole layer 4 with a space left between both the layers. An end surface 4a of the auxiliary magnetic pole layer 4 and an end surface 5a of the main magnetic pole layer 5 appear at an opposing surface Ha of the head positioned opposite to a recording medium M. The auxiliary magnetic pole layer 4 and the main magnetic pole layer 5 are magnetically coupled to each other in a magnetic coupling portion 6 located inward of the opposing surface Ha.
A nonmagnetic insulating layer 7 made of inorganic materials, such as Al2O3 and SiO2, is positioned between the auxiliary magnetic pole layer 4 and the main magnetic pole layer 5. In the opposing surface Ha, an end surface 7a of the nonmagnetic insulating layer 7 appears between the end surface 4a of the auxiliary magnetic pole layer 4 and the end surface 5a of the main magnetic pole layer 5.
Then, a coil layer 8 made of conductive materials, e.g., Cu, is embedded in the nonmagnetic insulating layer 7.
Also, as shown in FIG. 38, the end surface 5a of the main magnetic pole layer 5 has a thickness hw smaller than a thickness hr of the end surface 4a of the auxiliary magnetic pole layer 4. A width size of the end surface 5a of the main magnetic pole layer 5 in the direction of track width (indicated by X in FIG. 38) defines a track width Tw that is much smaller than a width size of the end surface 4a of the auxiliary magnetic pole layer 4 in the direction of track width.
The recording medium M, on which magnetic data is to be recorded by the perpendicular magnetic recording head H, is moved in the Z-direction relative to the perpendicular magnetic recording head H. The recording medium M has a hard surface Ma on the outer surface side and a soft surface Mb on the inner side.
When a recording magnetic field is induced in both the auxiliary magnetic pole layer 4 and the main magnetic pole layer 5 upon energization of the coil layer 8, a leaked recording magnetic field passes between the end surface 4a of the auxiliary magnetic pole layer 4 and the end surface 5a of the main magnetic pole layer 5 while perpendicularly penetrating the hard surface Ma of the recording medium M and propagating in the soft surface Mb. Since the end surface 5a of the main magnetic pole layer 5 has an area much smaller than that of the end surface 4a of the auxiliary magnetic pole layer 4 as described above, magnetic flux Φ is concentrated on a portion of the recording medium opposing to the end surface 5a of the main magnetic pole layer 5. Thus, magnetic data is recorded in a portion of the hard surface Ma opposing to the end surface 5a with the concentrated magnetic flux Φ.
However, the conventional perpendicular magnetic recording head H, shown in FIG. 38, has the following problems.    (1) In the structure shown in FIG. 38, an upper surface of the nonmagnetic insulating layer 7 has a certain degree of roughness, and therefore the main magnetic pole layer 5 formed on the upper surface of the nonmagnetic insulating layer 7 has reduced pattern accuracy. On the other hand, it is particularly required not only to reduce the area of the end surface 5a of the main magnetic pole layer 5, which appears at the opposing surface Ha, so that the leaked recording magnetic field is highly concentrated, but also to narrow the track width Tw defined by the end surface 5a for achieving a high recording density on the recording medium M.
Accordingly, the structure shown in FIG. 38 causes a difficulty in forming the end surface 5a of the main magnetic pole layer 5 so as to provide a smaller track width Tw and hence a narrower track with high pattern accuracy. Thus, the conventional structure is not satisfactorily adaptable for a higher recording density.    (2) In order to introduce, to the opposing surface Ha, a magnetic field induced from the coil layer 8, an inward area of the main magnetic pole layer 5 is required to have a larger cross-sectional area through which the magnetic flux is allowed to pass. In the structure shown in FIG. 38, however, the main magnetic pole layer 5 is formed to extend rearward in the height direction (indicated by Y in FIG. 38) with a substantially constant film thickness, and the film thickness of the main magnetic pole layer 5 cannot be increased in the inward area thereof. Hence, the magnetic field induced from the coil layer 8 cannot be effectively introduced to a fore end of the main magnetic pole layer 5.    (3) Since the main magnetic pole layer 5 is formed as a single layer in the structure shown in FIG. 38, it is difficult to extremely reduce only the track width Tw defined by the end surface 5a of the main magnetic pole layer 5. Stated otherwise, the main magnetic pole layer 5 is formed by forming a holed pattern on a resist layer and then applying a magnetic material to the holed pattern by, e.g., plating. Such a process has a difficulty in extremely reducing the width size of the holed pattern only in a portion where the end surface 5a is to be formed.    (4) When the slider 1 is moved between an outer periphery and an inner periphery of the recording medium M in the form of a disk, the end surface 5a of the main magnetic pole layer 5 is sometimes inclined and causes a skew angle with respect to the tangential direction of rotation of the recording medium M (i.e., the Z-direction in FIG. 38). In the case of the end surface 5a of the main magnetic pole layer 5 being square or rectangular as shown in FIG. 39, if the end surface 5a of the main magnetic pole layer 5 has a skew angle with respect to the tangential direction of rotation of the recording medium (i.e., the Z-direction in FIG. 38), a lateral side 5b of the main magnetic pole layer 5 provides an inclined leaked magnetic field within a track width Tw1, as indicated by a broken line, whereby fringing F occurs and off-track characteristics deteriorate.